1. Field of the Invention
The present invention relates to a chemical detection system which uses computer vision technology for chemical monitoring and/or identification using invertebrates, especially insects. It also relates to methods for using the system to monitor and/or identify chemicals.
2. Description of the Related Art
Detector systems have played an integral and beneficial role in our culture for many years. Governmental institutions, medicine, agriculture, education, industry, and households rely on chemical and physical detectors for safety, quality control, research and communication. Gas chromatography and mass spectrometry have advanced the understanding of chemistry and the ecology and physiology of species (Olson et al., Physiol. Entomol., 1999, volume 25, 17-26, 2000; Pare et al., Plant Physiol., Volume 114, 1161-1167, 1997), and x-rays and laser imaging have provided a means for detecting pathologies (Boice et al., JAMA, Volume 265, 1290-1294, 1991; Graham-Rowe, New Scientist, Volume 159, 24, 1998), including the quality of foods (Price et al., Food Technology, Volume 44, 6, 1990). Radar sensors are used internationally for communication, navigation, and entertainment (Galatie et al., Iee Proceedings-RADAR, SONAR and Navigation, Volume 144, 156-162, 1997) and Doppler radar systems monitor global weather patterns (Condella, Earth, Volume 7, 56-58, 1998). Near-infrared detectors monitor general vegetation health in agricultural systems (Bosch, Precision Farming: 20-24, 1997), accelerometers are used in cars to detect crash and signal deployment of airbags, and detectors are installed in homes to indicate the presence of harmful radiation, chemicals, and smoke (Edgerton et al., Environ. Science & Technology, Volume 20, 803-807, 1986; Lamarine et al., J. Community Health, Volume 17, 291-401, 1992).
Many of our technological developments have already been adapted from nature, for example, sonar, gyroscopes, heating and air conditioning, aviation, polyester, etc. (Au, Bioacoustics, Volume 8, 137-162, 1997; Engels et al., Studies on Neotropical Fauna and Environment, Volume 30, 193-205, 1995; Sherman, Agricultural Research, Volume 37, 18, 1989). However, with the exception of capturing the bioluminescence of fireflies, beeswax from bees, and the use of domestic animals as detectors (Cherfas, New Scientist, Volume 122, 45, 1989; King et al., Nature, Volume 249, 778-781, 1990), reliance on nature as models for technological development has been generally lacking. Only recently are investigations in the areas of robotics and biomimetics (Goldner, R & D Magazine, Volume 35, 77, 1993; Shimozawa, Rob. Autom. Syst., Volume 18, 75-82, 1996; Srinivasan, Materials Science & Engineering C-biomimetic Materials Sensors and Systems, Volume 4, 19-26, 1996; Weibecker et al., Talanta, Volume 44, 2217-2224, 1997) discovering nature's potential as models for technological development.
Domesticated animals, particularly dogs, have been relied upon as detectors. Historically, humans and domesticated animals have had a close association and many of these species have an incredible ability to detect objects and scents. Humans have been able to harness these abilities largely through training because of their ability to learn. Dogs have been successfully trained to detect narcotics, accelerants used in arson, and explosives, including landmines, and to track game and missing persons in search and rescue operations. However, the learning process and human relationship with these domesticated animals to create the responses to trained stimuli has never been totally understood. It is known that these animals often traverse and operate as effective detectors in less natural arenas, possibly because their historic domesticity has allowed them many years of adaptation to these environments. This ability has provided us with a means to utilize these trained and reliable detectors for our benefit in many different environments.
The U.S. Army Center for Environmental Health and Research (USCEHR) has devised a method for using bluegill sunfish (Lepomis macrochirus) for monitoring a broad range of toxins in water (http://usacehr.detrick.army.mil/envsen2.html). The aquatic biomonitor uses mounted electrodes to monitor signals generated in the water by the movement of the fish. When six or more of the eight parameters are detected as abnormal, the system initiates an alert. The system responds within an hour to most chemicals at toxic levels. This aquatic biomonitor is currently being implemented in a New York City reservoir.
Research by APOPO at the Sokoine University of Agriculture in Tanzania has led to the development of a successful regiment for training African Giant Pouched Rats (Cricetomys gambianus) to non-destructively detect landmines and accurately detect tuberculosis (http://www.apopo.org). The rats are capable of residual explosive scent tracing (REST) and direct detection of buried mines. The rats can be brought samples for identification or taken out and led through suspected mine fields. For tuberculosis detection, the rats have shown success in discriminating between positive and negative sputum samples without the need for expensive test equipment.
Insentinel Ltd. (Hertforshire, UK) has successfully devised a system using honeybees (Apis mellifera[Hymenoptera: Linnaeus]) for trace vapor detection (http://www.inscentinel.com). Using image recognition software, Insentinel bees can be monitor for the activity of a response to the target odor. The systems electronic output can notify a user of the presence of a single target odor.
Detecting volatile chemicals is becoming a leading method of non-invasive searching. Historically, the detection of volatiles has been very important in tracking illegal substances and detecting explosives, but it also has been shown to be a viable means of detecting other organic materials (Rains et al., unpublished, 2003). With the advancing needs of precision agriculture and homeland security, efforts are being made to lower the costs and increase the efficiency of screening through the use of volatile detection. Traditional methods of detecting volatile chemicals include human olfaction, canine training, and electronic olfaction (Gardner and Bartlett, Electronic noses: Principles and Applications, Oxford University Press, Inc., New York, 1998). Of these, human and dogs are the most sensitive, however both can be subjective and costly (Garnder and Bartlett, 1998, supra). Many electronic devices have been developed in response to the cost and reliability associated with volatile detection and range in design from simple, such as a metal oxide doped transistor, to complex, such as an array of polymer-coated sensors analyzed using neural networks. The simple designs are relatively inexpensive but are normally very specific and sensitive to low concentrations, or they detect a wider range of volatiles but lack sensitivity (Gardner and Bartlett, 1998, supra; Dicknson, TIBTECH, Volume 16, 250-258, 1998; Börgesson et al., Cereal Chemistry, Volume 73 (4), 457-461, 1996). More elaborate electronic nose designs are inexpensive relative to training and maintaining a canine, but are about 100 times less sensitive than human olfaction (Raman and Gerhardt, Transactions of the ASAE, Volume 40 (6), 1699-1707, 1997; Sarig, J. Aric. Engng Res., Volume 77 (3), 239-258, 2000), and the user is left to interpret the complex output (Rains et al., ASAE Meeting Paper No. 01-1069, 2001).
Although existing chemical detectors are specific and reliable and have allowed major advances in our ability to monitor for target chemicals, there remains a need in the art for chemical detector-systems that have sensitivity, programmability, portability, and a cryptic nature that are needed for many current problems requiring detection and monitoring. The present invention provides a system and method of chemical detection which is different from prior art methods.